Date: Wed, 25 Sep 1996 11:23:56 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: wpaul@skynet.ctr.columbia.edu (Bill Paul) Cc: jhs@FreeBSD.org, current@FreeBSD.org, serious@FreeBSD.org, commercial@FreeBSD.org Subject: Re: Licensing Software Message-ID: <199609251823.LAA06357@phaeton.artisoft.com> In-Reply-To: <199609251416.KAA22427@skynet.ctr.columbia.edu> from "Bill Paul" at Sep 25, 96 10:16:24 am
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> Think hard about this. It's not as easy as it may first appear. With > PCs, you can swap out practically all the hardware, particularly ethernet > cards, so trying to find a hardware ID value that doesn't change is a > real challenge. > > Another problem with using ethernet addresses is that you need to > grovel around in /dev/kmem in order to get them. This would require your > executable to be setgid kmem in order to work. No. If you use *IP* address, you don't have this problem. In point of fact, there was a recent discussion on the SCO and Linux ABI front that determined that you could get ethernet hardware addresses for any given real ethernet interface using one of the ABI routines. So you can forget about having to grovel kmem. I specifically referenced IP addresses in my discussion because: 1) ifconfig will fail to operate if you hack the interface it uses so that it lies about IP address to your license daemon. 2) Your network will fail to operate if two machines are given the same IP address; they won't both work at the same time; it depends on who gets into what ARP table when, and even then, it won't necessarily be functional. 3) You could safely hack the ethernet address return interface and no one would be the wiser because no system software components really depends on it. 4) LANCE interfaces on DEC and Sun harware can have their address reprogrammed. This is practically true of any ethernet card capable of supporting DECNet or DECNet bridging/routing. The Novell/Excellan "LANalyzer" card is one example of a PC card which can do this. 5) The ethernet address (as opposed to the IP address) is a 48 bit value, and therefore unsuitable for use by hostid. 6) Using the IP address for the hostid return is traditional. > I also wanted to try to find a way around the awful flaw in FLEXlm that > makes it practically worthless. It sort of worked, but I got bored with > it after a while and let it languish. Heh. I forgot about that one. Yeah, that's a bit of a problem, isn't it? I remember the day we found out about it; we were using Framemaker. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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